Head spinning! Seeking advice for tire/wheel fit, '66 Barracuda.

I'm running 7 inch wide on rear with 4 1/4 back space 215 tires, front is 6 inch wide with 4 inch back space 215 tires also the front tires will be changed soon too tall don't like the look. They are ralley wheels, not much room to work with in the rear with out moving springs inboard. When you get done let us know what you ended up with size wize i've been thinking about tire sizes for months hard to tell what will work with out stuffing them in there and test fitting i don't want to cut up the car. I am a firm beliver in stuff as wide a tire under the fenders as possible without cutting.